Pyrometric cones having regions of varied densities



Nov. 24, 1970 R. a. sun: ETAL 3,541,;56

PYROIBTRIC CONES HAVING REGIONS OF VARIED DENSI'IIES "10d D00. 3, 1968 2 Sheets-Sheet 1 I I M L I I'M mvmons RICHARD E. STEELE MlLAN VUKOVICH JR L. SCOTT H000, JR

9m MMflr/a I l M... Z {a ATTORNEY Nov. 24, 1970 R. E. STEELE ErAL 3,541,856

PYROBETRIC CONES HAVING REGIONS 0F VARIED DENSITIES ".104 Doc. 2, 1968 2 Sheets-Sheet 2 mvmoas RICHARD E. STEELE MILAN vumvncmm. L. SCOTT HOOD, JR.

wmwwmw ATTORNEY United States Patent 3,541,856 PYROMETRIC CONES HAVING REGIONS OF VARIED DENSITIES Richard E. Steele, Columbus, and Milan Vukovich, Jr., Galena, Ohio, and Leroy Scott Hood, Jr., Raleigh, N.C.. assignors to The Edward Orton, Jr., Ceramic Foundation, a testamentary trust under the laws of Ohio, Columbus, Ohio Filed Dec. 2, 1968, Ser. No. 780,427 Int. Cl. B2811 3/08; G011: 11/08 [1.5. CI. 73-358 12 Claims ABSTRACT OF THE DISCLOSURE A heat treatment measuring system and a method of using such system wherein a pyrometric cone having varied densities in the regions defining the side surfaces thereof is placed in an upright attitude in the environment of a heat treatment process. The cone is oriented in the environment so that when the amount of heat applied during the process is sufficient to fuse the material from which the cone is made, the cone will bend over the side surface thereof defined by the region of least density.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to pyrometric cones. Specifically, the invention concerns pyrometric cones which are made by compacting substantially dry granular material and which as a result of such compaction have regions of varied densities.

Description of the prior art Pyrometric cones long have been used for measuring the amount of heat applied during heat treatment processes, particularly ceramic ware firing processes. Such cones conventionally are placed in the environment of a heat treatment process, such as in a kiln, and subjected to the same heating conditions as the ware. After an individual cone has been subjected to a predetermined amount of heat, the amount of heat being a function of temperature and time of exposure, the material from which the cone is made fuses, and the cone bends over to provide a visual indication of the amount of heat applied to the Ware. The cones are made from various ceramic materials, each such material providing cones which are sensitive to a different predetermined amount of heat, and therefore may be used for measuring the amount of heat applied in a wide range of heat treatment processes.

To function properly, the fusing and bending characteristics of all cones of like composition should be substantially identical. Otherwise, the cones would fail to provide a consistent and accurate indication of the amount of heat applied during a heat treatment process.

One of the physical properties of a pyrometric cone which affects its fusing and bending characteristics is a difference between the densities of two or more regions thereof. Ideally, the density of each cone should be uniform throughout. However, it has been found that a cone which is made by compacting or pressing substantially dry granular material, known as a dry pressed cone, while having many advantages over cones made by molding and casting processes, does not have a uniform density throughout. In particular, it has been found that the regions of a dry pressed cone that are closest to the compacting or pressing elements which exert the greatest compression forces on the material when the cone is made, for example the regions closest to one or more movable punches, have greater densities than other regions of the cone.

Known methods and apparatus for making dry pressed cones are disclosed in C0 Van et al. Pat. 2,129,912, Bole et a1. Pat. 2,181,618 and Co Van et al. Pat. 2,181,619. The dry pressed cones in common use today are made by methods and apparatus similar to those disclosed in these patents. As mentioned, however, such cones possess internal density variations which affect their fusing and bending behavior. Therefore, while it is desirable to retain the compaction or pressing process of making pyrometric cones, consistency of cone behavior requires that the density variations resulting from such process be controlled, and that the manner in which dry pressed cones are used be adjusted so that density variations will have a minimal effect on cone fusing and bending characteristics.

SUMMARY OF THE INVENTION The present invention oifers an optimum solution to the problems associated with the aforementioned density variations of dry pressed pyrometric cones, by providing a method of using such cones wherein the fusing and bending characteristics of all cones of like composition are consistent.

Also, the invention encompasses a dry pressed pyrometric cone in which the distribution of the density variations resulting from the compaction process by which the cone is made, is known, thus permitting the thermal deformation characteristics of the cone to be accurately controlled.

Additionally, the invention includes an apparatus which is particularly designed for making such a cone.

As described in application Ser. No. 758,346, filed Sept. 9, 1968, and owned by the assignee of the present application, the performance of pyrometric cones made by any process is most accurately regulated when the cones are employed as an integral part of a heat treatment measuring system that includes means for supporting and holding the cones in a predetemined upright attitude. Accordingly, the present invention also embraces a heat treatment measuring system in which one or more dry pressed cones are supported and held in such a manner as to minimize any adverse effects that might be caused by density variations. The heat treatment measuring system preferably employs the dry pressed pyrometric cones of the present invention but may utilize cones having regions of different densities made by other methods.

The present invention is predicated upon the discovery that the regions of a dry pressed pyrometric cone which are of different densities exhibit different fusing and deformation characteristics when the cone is subjected to heating. While all of the parameters which influence fusing and deformation may not be known, it is believed that a greater amount of shrinking occurs in the regions of lower density than in the regions of higher density. This shrinkage difference tends to cause a dry pressed cone to deform or bend in the direction of the region of least density. Such density-influenced bending frequently causes twisting and distortion, resulting in wide variations in cone performance and providing false or misleading indications of the heating conditions that exist in the environment of a heat treatment process.

Recognizing this problem, the present invention contemplates a method of utilizing dry pressed pyrometric cones wherein such a cone is placed in an upright attitude in the environment of a heat treatment process and is oriented in the environment so that when the amount of heat applied during the process is sufiicient to fuse the material from which the cone is made, the cone will bend over the side thereof defined by the region of least density. Thus, the cone is purposely supported and held in such a manner that the desired direction of deformation is the direction towards which its least dense region is oriented. When so supported and held, the natural propensity of a dry pressed cone to bend in the direction of its least dense region is exploited not only to induce the cone to bend in the desired direction but also to minimize spurious density-influenced bending.

Basically described, the pyrometric cone of the invention is made by compacting granular material having a moisture content of no greater than 15% by weight at ambient temperature, and is shaped as a truncated, triagonal pyramid defined by an upper, lower and three side surfaces, wherein the density of the cone in the regions thereof defining two of the side surfaces is approximately equal and the density of the cone in the region thereof defining the other of the side surfaces is substantially less than the density in the first-mentioned regions.

The heat treatment measuring system of the invention basically comprises, at least one pyrometric cone shaped as a truncated, triagonal pyramid having an upper, lower and three side surfaces and having varied densities in the regions thereof defining the side surfaces, a plaque for supporting the cone, and means for holding the cone on the plaque in an upright attitude, wherein the cone is held on the plaque with the one side surface which is defined by the region of the cone of least density oriented in the desired direction of cone bending upon fusion of the material from which the cone is made.

The apparatus of the invention is particulaly designed for making an article of manufacture comprising two of the aforementioned pyrometric cones which are connected together in side-by-side relationship by a web of the material from which the cones are made. The cones may be easily separated by hand or suitable mechanical means by breaking or severing the web.

The apparatus basically comprises; a die block having an opening of substantially uniform cross section therethrough defined by a plurality of walls, a pair of cooperating punches receivable in opposite ends of the die block opening for compacting substantially dry granular material therebetween and the walls defining the opening upon relative movement of the punches toward each other, each of the punches having a punch face for engaging the material, each punch face being shaped to form one of the two side surfaces defined by the regions of greater density of each cone so that upon relative movement of the punches toward each other said two side surfaces of each cone are formed by the punch faces and the one side surface defined by the region of least density of each cone is formed by one of the walls defining the die block opening, and means for moving the punches relatively toward each other.

As will be apparent from this brief description, the present invention comprehensively embraces a method of using dry pressed pyrometric cones, a heat treatment measuring system which employs dry pressed cones, a dry pressed pyrometric cone, an article of manufacture comprising two such dry pressed cones, and an apparatus for making such article.

With the foregoing in mind, it is an object of the present invention to provide a method of using a pyrometric cone having regions of varied densities wherein such varied densities are precluded from causing spurious density-infiuenced cone bending.

It is also an object of the invention to provide a method of using a dry pressed pyrometric cone wherein the cone is supported and held so that it will bend in the direction of its least dense region when subjected to a sufficient amount of heat to cause the material from which it is made to fuse.

It is a further object of the invention to provide a pyrometric cone made by compacting substantially dry granular material in which the distribution of density variations is known to thus permit the fusing and bending characteristics of such cone to be accurately controlled.

It is another object of the invention to provide a dry pressed pyrometric cone shaped as a truncated, triagonal pyramid having three side surfaces wherein the density of the cone in the regions thereof defining two of the side surfaces is approximately equal and greater than the density of the cone in the region thereof defining the other of the side surfaces.

It is a further object of the invention to provide a heat treatment measuring system in which a dry pressed pyrometric cone is supported and held with the region thereof of least density oriented in the desired direction of cone bending.

It is yet another object of the invention to provide an article of manufacture comprising two dry pressed pyrometric cones connected together in side-by-side relationship.

It is an additional object of the invention to provide an apparatus for making an article of manufacture comprising two dry pressed pyrometric cones connected together in side-by-side relationship.

The foregoing and other objects of the invention will become apparent upon a consideration of the following detailed description of the preferred embodiments thereof given in connection with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a portion of the apparatus of the present invention;

FIG. 2 is a vertical sectional view of the apparatus shown in FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is a sectional view taken on line 44 of FIG. 1;

FIG. 5 is a perspective view of the article of manufacture of the present invention comprising two dry pressed pyrometric cones connected together in side-by-side relationship;

FIG. 6 is a plan view of the article of manufacture shown in FIG. 5;

FIG. 7 is an end view of the article of manufacture shown in FIG. 5;

FIG. 8 is an end view of two of the pyrometric cones of the present invention; and

FIG. 9 is an end view of the heat treatment measuring system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Two of the dry pressed pyrometric cones of the invention are shown in FIG. 8, as designated by reference numerals l and 20. Both conues are made by compacting a substantially dry granular ceramic material and preferably a granular ceramic material having a moisture content of no greater than 15% by weight at ambient temperature. As shown in FIG. 8, the cones are shaped as truncated, triagonal pyramids with cone 10 having an upper surface 1.1, a lower surface 12 and three side surfaces 13, 14 and 15, and cone 20 having similar upper, lower and side surfaces designated by reference numerals 21, 22, 23, 24 and 25, respectively. The pyramidal shape of cones 10 and 20 is conventional for pyrometric cones and forms no part of the present invention.

Cones 10 and 20 are made as integral parts of the article of manufacture of the invention shown in FIGS. -7, as designated by reference numeral 30. Article 30 comprises cones and connected together in side-byside relationship by a web 32 of the material from which the cones are made. The cones may be easily separated by hand or suitable mechanical means by breaking or severing web 32.

Article is made by the apparatus of the invention, a punch press, shown in FIGS. l-4, as designated by reference numeral 40. Press includes a die block 42 and a pair of punches 44 and 46.

Die block 42 has an opening 48 of substantially uniform cross section therethrough defined by walls 50. Punches 44 and 46 are receivable in the opposite ends of opening 48 and are reciprocated relatively toward and away from each other by a conventional punch driving mechanism 52, shown schematically in FIG. 2. The transverse cross section of each punch is shaped as a parallelogram and the cross section of opening 48 is similarly shaped so that Walls 50 closely surround the punches when they are moved within opening 48 by mechanism 52. The punches are adapted to compress substantially dry granular ceramic material between the punches and walls 50 when the punches are moved into close proximity with one another within opening 48, as shown in FIGS. 2 and 3.

Punches 44 and 46 have punch faces 54 and 56, respectively, for engaging the granular material. The punch faces are similarly configured each including a pair of truncated, substantially triangularly shaped surfaces 58 and 60 which are connected together in side-by-side relationship by a narrow rib 62. As best shown in FIGS. 1, 3 and 4, rib 62 comprises the forward extremity of each punch face, with triangularly shaped surfaces 58 and 60 being connected to the rib along one of their respective sides and sloping backwardly from the rib on opposite sides thereof. The truncated apex of each surface 58 is disposed adjacent the base of the associated surface 60 and the truncated apex of each surface 60 is disposed adjacent the base of the associated surface 58.

Punches 44 and 46 are oriented relative to one another so that when they move into close proximity with each other within opening 48, the rib 62 of one punch face will be directly opposed to the rib 62 of the other punch face and the triangularly shaped surfaces 58 and 60 of one face will be directly opposed to the corresponding surfaces of the other face. As will be apparent when granular material is compacted between the punches and the walls of the die block opening, each of the triangularly shaped surfaces of each punch face will form one of the side surfaces of each of cones and of article 30, and in particular side surface 14 of cone 10 and side surface 24 of cone 20 will be formed by the triangularly shaped surfaces 58 and 60, respectively, of punch face 56, whereas side surface 13 of cone 10 and side surface 23 of cone 20 will be formed by the triangularly shaped surfaces 58 and 60, respectively, of punch fact 54. The third side surface, and upper and lower surfaces of each cone will be formed by the walls 50, and in particular side surface 15, upper surface 11 and lower surface 12 of cone 10, and side surface 25, upper surface 21 and lower surface 22 of cone 20 will all be formed by walls 50. Web 32 which connects cones 10 and 20 will be formed by ribs 62.

When a quantity of granular material is compacted between punches 44 and 46, and walls 50, the greatest localized compression forces will be exerted on the regions of the material which are closest to punch faces 54 and 56 and those same regions of article will have a greater density than any other region of the article. Thus, the regions of cone 10 defining side surfaces 13 and 14, and the regions of cone 20 defining side surfaces 23 and 24 will have a greater density than any other regions of the cones. Conversely, the regions of cones 10 and 20 defining side surfaces 15 and 25, respectively, will be substantially less dense than the regions thereof defining side surfaces 13 and 14, and 23 and 24, respectively, because the material which forms the former regions will be subjected to substantially lesser localized compression forces than the material which forms the latter regions.

As will be evident, if punches 44 and 46 are moving at approximately the same velocity relative to die block 42 at the instant just prior to compaction, the density of cones 10 and 20 in the regions thereof defining side surfaces 13 and 14, and 23 and 24, respectively, will be approximately equal. This is the preferred mode of operating press for a reason which will be explained hereinbelow. If one of the punches is held stationary at the instant just prior to compaction, the regions of the cones defining the side surfaces closest to the stationary punch will be less dense than the regions of the cones defining the side surfaces closest to the moving punch. However, irrespective of whether both punches are moving or one punch is held stationary at the instant just prior to compaction, the density of the cones in the regions thereof closest to the punch faces will be substantially greater than the regions thereof closest to walls 50, since in both instances the former regions are subjected to much greater localized compression forces than the latter regions.

The article of manufacture made by press 40, article 30, is a coherent solid article of the shape shown in FIGS. 5-7, with cones 10 and 20 being connected to web 32 along the edges thereof defined by the intersection of the side surfaces thereof defined by the regions thereof of greatest density, and in particular along the edges defined by the intersection of side surfaces 13 and 14 of cone 10, and side surfaces 23 and 24 of cone 20. When the cones are separated they are ready for use.

As discussed in aforementioned application Ser. No. 758,346, pyrometric cones made by any process perform best when they are employed as an integral part of a heat treatment measuring system that includes means for supporting and holding the cones in a predetermined upright attitude. Such a system is shown in FIG. 9, as designated by reference numeral 70, and includes a pyrometric cone 72 which may be any dry pressed cone but preferably is of the type hereinbefore described with respect to cones 10 and 20.

System also includes a plaque 74 for supporting cone 72 and a means for holding the cone on the plaque in the desired upright attitude, such as a. suitable ceramic adhesive 76 applied to the lower portion of the cone. A detailed description of heat treatment measuring systems similar to system 70 appears in the aforementioned application, including a discussion of the advantages obtained by using such a system.

As is relevant to the present invention, dry pressed cone 72 is held on plaque 74 so that its side surface which is defined by the region thereof of least density is oriented in the desired direction of cone bending. With respect to system 70, the desired direction of cone bending is indicated by arrow 80. Accordingly, the side surface of cone 72 which is defined by the region thereof of least density is oriented towards and faces the right as seen in FIG. 9, and as designated by reference numeral 78. When cone 72 is heated a sufficient amount to cause the ceramic material from which the cone is made to fuse, it will bend over side surface 78 in the direction of arrow 80. This arrangement not only minimizes spurious density-infiuence bending but provides the further advantage of positively inducing the cone to bend in the desired direction. If cone 72 is of the type described hereinabove with respect to cones 10 and 20, such cones are held on plaque 74 with side surfaces 15 and 25 thereof, respectively, oriented similarly to side surface 78 of cone 72.

As mentioned above, with respect to the operation of press 40, it is preferred that the regions of cones 10 and 20 defining the side surfaces thereof formed by punch faces 54 and 56, namely the regions defining side surfaces 13 and 14, and 23 and 24 of cones 10 and 20, respectively, be of approximately equal density. The reason for this preference will now be apparent. When cones 10 and 20 are properly oriented for measuring the amount of heat applied during a heat treatment process, the most dense regions of each cone are disposed symmetrically about a plane defined by the cone axis and a line normal thereto oriented in the desired direction of cone bending. If the density of such symmetrically disposed regions is approximately equal, the density-influenced bending effects produced by one region will be approximately equal, but acting oppositely, to the density-influenced bending effect-'1 produced by the other region, and the effects produced by one region will therefore tend to cancel or nullify the effects produced by the other. The net result of such cancellation thus constitutes an additional factor which induces the cones to bend only in the desired direction.

From the foregoing description of heat treatment measuring system 70, the method of the present invention will be apparent. Such method embraces the steps of placing a dry pressed pyrometric cone in an upright attitude in the environment of a heat treatment process, orienting the cone in the environment so that when the amount of heat applied during the process is sufficient to fuse the material from which the cone is made, it will bend over the side surface thereof defined by the region thereof of least density, and allowing said cone to remain in the environ ment during the process at least until the material fuses and the cone bends over. Preferably, the cones used in carrying out this process have the preferred density distribution described hereinabove since the most dense regions of such cones are of approximately equal density and, as discussed above, tend to produce equal but ppositely acting density-influenced bending effects.

The foregoing constitutes a detailed description of the preferred embodiments of the invention, including a method of using a dry pressed pyrometric cone which minimizes spurious density-influenced cone bending, a heat treatment measuring system which employs dry pressed cones for carrying out the method of the invention, a dry pressed cone having an optimum density distribution, and an apparatus for making such cone.

It is recognized that while the foregoing constitutes a detailed description of the invention, various modifications thereof will occur to those skilled in the art. Accordingly, the scope of the invention is to be limited solely by the scope of the claims appended hereto.

We claim:

1. A pyrometric cone made by compacting substantially dry granular material, said cone being shaped as a truncated, triagonal pyramid defined by an upper, lower and three side surfaces, the density of said cone in the regions thereof defining two of said side surfaces being approximately equal, and the density of said cone in the region thereof defining the other of said side surfaces being less than said density in the regions defining said two side surfaces.

2. An article of manufacture made by compacting substantially dry granular material, comprising two pyrometric cones connected together in side-by-side relationship by a web of said material, said cones each being shaped as a truncated, triagonal pyramid defined by an upper, lower and three side surfaces, the density of each cone in the regions thereof defining two of said side surfaces being greater than the density of each cone in the region thereof defining the other of said side surfaces.

3. An article of manufacture as recited in claim 2, wherein said cones are connected to said web along the edge of each of said cones defined by the intersection of said two side surfaces.

4. An article of manufacture as recited in claim 2, wherein the upper surface of each of said cones is disposed adjacent the lower surface of the other of said cones.

5. In a heat treatment measuring system comprising at least one pyrometric cone shaped as a truncated, triagonal pyramid having an upper, lower and three side surfaces and having varied densities in the regions thereof defining said side surfaces, a plaque for supporting said cone, and means for holding said cone on said plaque in an upright attitude; the improvement wherein said cone is held on said plaque with the one of said side surfaces defined by the region thereof of least density oriented in the desired direction of cone bending.

6. A heat treatment measuring system as recited in claim 5; wherein the density of said cone in the regions thereof which define two of said side surfaces is greater than the density of said cone in the region thereof defining the other of said side surfaces; and wherein said other side surface is oriented in the desired direction of cone bending.

7. A heat treatment measuring system as recited in claim 6, wherein the density of said cone in the regions thereof defining said two side surfaces is approximately equal.

8. An apparatus for making an article of manufacture composed of substantially dry granular material and comprising two pyrometric cones connected together in sideby-side relationship by a web of said material, said cones each being shaped as a truncated, triagonal pyramid defined by an upper, lower and three side surfaces, the density of each cone in the regions thereof defining two of side surfaces being greater than the density of each cone in the region thereof defining the other of said side surfaces said apparatus comprising:

a die block having an opening of substantially uniform cross section therethrough defined by a plurality of walls;

a pair of cooperating punches receivable in opposite ends of said opening for compacting said material therebetween and said walls upon relative movement of said punches toward each other, each of said punches having a punch face for engaging said material, each said face being shaped to form one of said two side surfaces of each of said cones so that upon relative movement of said punches toward each other said two side surfaces of each of said cones are formed by said faces and said one side surface of each of said cones is formed by one of said walls; and

means for moving said punches relatively toward each other.

9. An apparatus as recited in claim 8, wherein each of said punch faces is defined by a pair of truncated, substantially triangularly shaped surfaces connected together in side-by-side relationship by a narrow rib.

10. An apparatus as recited in claim 9, wherein said triangularly shaped surfaces defining each of said faces are connected to said rib along a side of each of said triangularly shaped surfaces.

11. An apparatus as recited in claim 10, wherein said rib constitutes the forward extremity of each of said faces and said triangularly shaped surfaces slope backwardly therefrom on opposite sides of said rib.

12. An apparatus as recited in claim 8, wherein the cross section of said opening is shaped as a parallelogram.

References Cited UNITED STATES PATENTS 2,129,912 9/1933 Covan 73358 2,181,618 11/1939 Bole 2590 2,181,619 11/1939 Co Van 25-90 2,274,343 2/1942 Orth 73358 LOUIS R. PRINCE, Primary Examiner D. E. CORR, Assistant Examiner US. Cl. X.R. 25-90 

